Vehicle seats are sometimes configured to be adjustable to fit a variety of seated vehicle occupants according to their individual sizes and comfort standards. For example, a vehicle seat back may be configured to tilt forward and backward relative to a seat bottom, and/or the entire vehicle seat may be configured to move forward and backward with respect to the floor of the vehicle. Portions of the seat may be configured for simultaneous or independent adjustment by the occupant.
In U.S. Pat. No. 7,458,294 to Dohles et al., a spindle or worm drive is described for use with adjustment devices in motor vehicles. The device is secured with a fixed spindle or a fixed tooth rack to the first of two parts and is provided with a gear mechanism connected to the second of the two parts. A bearing shell encloses the gear housing and includes multiple pieces welded together to provide structure completely around the gear housing before it is attached to the second of the two parts to make it adjustable relative to the first of the two parts.